That's not vermetid snail (THE White curl SP) It's like @JGT say spirorbid , nothing relied with vermetidThose are not spirorbid snails. They are smaller vermetids. Spirorbids are much smaller and will grow on glass and rock in low flow areas but are flat and the end of their shell doesn't come outward/upward like the vermetids do, as you can see in the last pic you posted there are several that are clearly pointing up away from the spiral body at the end.